This invention relates to tissue fasteners, in particular to devices for attaching soft tissue (e.g., tendons, ligaments, or cartilage) to bone or to other soft tissue.
One conventional tissue fastener used to re-attach cartilage to bone comprises an elongated shaft with a series of barbs that enable the shaft to be inserted through tissue but resist withdrawal thereafter. The distal tip of the shaft is sharp, and the proximal end of the shaft terminates at an enlarged head. To re-attach soft tissue to bone, the fastener is pushed through the soft tissue into a pre-formed hole in the bone until the soft tissue is secured between the head and the bone surface. The barbs resist withdrawal from the hole, thereby holding the fastener (and thus the soft tissue) in place.
One aspect of the invention features a tissue fastener comprising a shaft having a member disposed thereon for lodging the shaft within the tissue, the shaft having a region that is relatively flexible to render a tissue engaging head disposed at a proximal end of the shaft movable with respect to the shaft.
Preferred embodiments may include one or more of the following features.
In one embodiment, the region comprises substantially an entire length of the shaft. The region comprises flexible material, such as a mesh. The member and the head are molded onto the mesh. The member comprises at least one barb.
In another embodiment, the shaft comprises generally rigid material, and the region comprises a flexible joint between the shaft and the head. The flexible joint comprises a breakable section of the shaft. For example, the section is constructed to be frangible (i.e., readily broken). A flexible member extends between the shaft and the head past the breakable section. The flexible member comprises, e.g., a plurality of filaments or a flexible tube. The flexible member extends along substantially an entire length of the shaft. The breakable section is defined by at least one opening disposed through a wall of the shaft. The shaft and the head comprise an integral molded unit, and the flexible member is molded therewithin.
The tissue fastener is made from polymeric material, such as a bioabsorbable material. The shaft is hollow and defines an interior passage. The head includes an opening in communication with the passage. The passage may be open or closed at a distal end of the shaft.
In one embodiment, the head has a flat distal surface. In another approach, the head has a toothed distal surface.
Another aspect of the invention features the tissue fastener and an insertion tool engageable with the tissue fastener for inserting the tissue fastener into tissue.
Preferred embodiments may include one or more of the following features. The tissue fastener member is disposed at a distal region of the shaft for lodging the shaft within the tissue, and the tissue engaging head is disposed at a proximal end of the shaft, and the shaft is relatively flexible between the member and the head. The insertion tool has an engagement portion for engaging the member. The head includes an aperture, and the engagement portion of the tool is configured to extend through the aperture when engaged with the member.
Other aspects of the invention feature methods for tissue attachment using the tissue fastener. One such method comprises inserting the tissue fastener through a first tissue and into a second tissue so that the member lodges within the second tissue and the head urges the first tissue against the second tissue.
Preferred embodiments may include one or more of the following features.
The first tissue and the second tissue are regions of a common tissue structure. For example, the tissue is cartilage and, prior to the inserting, the first region is separated from the second region by a tear in the cartilage.
Alternatively, the first tissue is soft tissue and the second tissue is bone.
Another aspect of the invention features a method for making a tissue fastener comprising providing a shaft having a member disposed thereon for lodging the shaft within the tissue, and a tissue engaging head disposed at a proximal end of the shaft, and making a region of the shaft relatively flexible to render the head movable with respect to the shaft.
Preferred embodiments include making the tissue fastener so as to have the structural features discussed above.
The flexibility of the tissue fastener allows the head to move (either from side to side or up and down) in response to loads imposed by the tissue, without compromising the security of the tissue attachment. As a result, healing is promoted even in high stress applications, with little risk of the head digging into, and potentially damaging, the tissue. The tissue fastener is particularly (but by no means exclusively) useful in the treatment of shoulder and knee instability, and in small joint repairs. These applications include meniscal repair, rotator cuff repair, Bankhart procedures, and treatment of xe2x80x9cslapxe2x80x9d lesions.
Other features and advantages of the invention will become apparent from the following description, and from the claims.